Tensor Decomposition-Based Channel Estimation and Sensing for Millimeter Wave MIMO-OFDM V2I Systems

An integrated sensing and communication(ISAC)scheme for a millimeter wave(mmWave)multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM)Vehicle-to-Infrastructure(V2I)system is presented,in which both the access point(AP)and the vehicle are equipped with large antenna arrays and employ hybrid analog and digital beamforming structures to compensate the path loss,meanwhile compromise between hardware complexity and system performance.Based on the sparse scattering nature of the mmWave channel,the received signal at the AP is organized to a four-order tensor by the introduced novel frame structure.A CANDECOMP/PARAFAC(CP)decomposition-based method is proposed for time-varying channel parameter extraction,including angles of departure/arrival(AoDs/AoAs),Doppler shift,time delay and path gain.Then leveraging the estimates of channel parameters,a nonlinear weighted least-square problem is proposed to recover the location accurately,heading and velocity of vehicles.Simulation results show that the proposed methods are effective and efficient in time-varying channel estimation and vehicle sensing in mmWave MIMOOFDM V2I systems.

基于IUDE算法的主动悬架H_(2)/H_∞控制

汽车高性能主动悬架对提升驾乘体验感具有显著优势,鲁棒性控制算法是发挥主动悬架性能的重要保障。针对典型鲁棒控制算法难以实现有效扰动估计和补偿的问题,本文提出了H_(2)/H_(∞)-H_(2)-IUDE算法,采用IUDE算法估计并补偿扰动,并引入H_(2)状态观测器,相比H_(2)/H_(∞)算法增强了鲁棒性。首先,建立了半车主动悬架控制系统模型,并定义了扰动形式。然后,提出能实现扰动估计和补偿解耦的IUDE算法,并提出一种H_(2)状态观测器,进而实现了对H_(2)/H_(∞)算法的再设计。最后,针对随机路面和减速带路面等典型工况进行仿真分析。结果表明,所提出的算法相比H_(2)/H_(∞)算法,随机路面工况的车身质心垂向加速度和俯仰角均方根值分别下降了7.6%和5.9%,对汽车平顺性有明显改善。同时,所提出的H_(2)观测器能有效估计系统状态,IUDE算法能准确估计扰动,并能够避免非解耦型UDE方法带来的悬架动挠度恶化问题,具有优异的扰动估计和灵活补偿的突出特点。

2-D algebraic test for robust stability of time-delay systems with interval parameters

The robust stability test of time-delay systems with interval parameters can be concluded into the robust stability of the interval quasipolynomials. It has been revealed that the robust stability of the quasipolynomials depends on that of their edge polynomials. This paper transforms the interval quasipolynomials into two-dimensional （2-D） interval polynomials （2-D s-z hybrid polynomials）, proves that the robust stability of interval 2-D polynomials are sufficient for the stability of given quasipolynomials. Thus, the stability test of interval quasipolynomials can be completed in 2-D s-z domain instead of classical 1-D s domain. The 2-D s-z hybrid polynomials should have different forms under the time delay properties of given quasipolynomials. The stability test proposed by the paper constructs an edge test set from Kharitonov vertex polynomials to reduce the number of testing edge polynomials. The 2-D algebraic tests are provided for the stability test of vertex 2-D polynomials and edge 2-D polynomials family. To verify the results of the paper to be correct and valid, the simulations based on proposed results and comparison with other presented results are given.

Recent advances in catalytic systems for CO_(2) conversion to substitute natural gas(SNG):Perspective and challenges

It has been well established that carbon dioxide(CO_(2))is one of the main greenhouse gasses and a leading driver of climate change.The chemical conversion of CO_(2) to substitute natural gas(SNG)in the presence of renewable hydrogen is one of the most promising solutions by a well-known process called CO_(2) methanation.There have been comprehensive efforts in developing effective and efficient CO_(2) methanation catalytic systems.However,the choice of competitive and stable catalysts is still a monumental obstruction and a great challenge towards the commercialization and industrialization of CO_(2) methanation.It is necessary to emphasize the critical understandings of intrinsic and extrinsic interactions of catalyst components(active metal,support,promoter,etc.)for enhanced catalytic performance and stability during CO_(2) methanation.This study reviews the up-to-date developments on CO_(2) methanation catalysts and the optimal synergistic relationship between active metals,support,and promoters during the catalytic activity.The existing catalysts and their novel properties for enhanced CO_(2) methanation were elucidated using the state-of-the-art experimental and theoretical techniques.The selection of an appropriate synthesis method,catalytic activity for CO_(2) methanation,deactivation of the catalysts,and reaction mechanisms studies,have been explicitly compared and explained.Therefore,future efforts should be directed towards the sustainable developments of catalytic configurations for successful industrial applications of CO_(2) utilization to SNG using CO_(2) methanation.

Adaptive control using interval Type-2 fuzzy logic for uncertain nonlinear systems

A new adaptive Type-2 （T2） fuzzy controller was developed and its potential performance advantage over adaptive Type-1 （T1） fuzzy control was also quantified in computer simulation. Base on the Lyapunov method, the adaptive laws with guaranteed system stability and convergence were developed. The controller updates its parameters online using the laws to control a system and tracks its output command trajectory. The simulation study involving the popular inverted pendulum control problem shows theoretically predicted system stability and good tracking performance. And the comparison simulation experiments subjected to white noige or step disturbance indicate that the T2 controller is better than the T1 controller by 0--18%, depending on the experiment condition and performance measure.

Abiotic-Biological Hybrid Systems for CO2 Conversion to Value-Added Chemicals and Fuels

Abiotic-biological hybrid systems that combine the advantages of abiotic catalysis and biotransformation for the conversion of carbon dioxide(CO2)to value-added chemicals and fuels have emerged as an appealing way to address the global energy and environmental crisis caused by increased CO2 emission.We illustrate the recent progress in this field.Here,we first review the natural CO2 fixation pathways for an in-depth understanding of the biological CO2 transformation strategy and why a sustainable feed of reducing power is important.Second,we review the recent progress in the construction of abiotic-biological hybrid systems for CO2 transformation from two aspects:(i)microbial electrosynthesis systems that utilize electricity to support whole-cell biological CO2 conversion to products of interest and(ii)photosynthetic semiconductor biohybrid systems that integrate semiconductor nanomaterials with CO2-fixing microorganisms to harness solar energy for biological CO2 transformation.Lastly,we discuss potential approaches for further improvement of abiotic-biological hybrid systems.

Stabilization of Discrete-time 2-D T-S Fuzzy Systems Based on New Relaxed Conditions

This paper is concerned with the problem of stabilization of the Roesser type discrete-time nonlinear 2-D system that plays an important role in many practical applications. First, a discrete-time 2-D T-S fuzzy model is proposed to represent the underlying nonlinear 2-D system. Second, new quadratic stabilization conditions are proposed by applying relaxed quadratic stabilization technique for 2-D case. Third, for sake of further reducing conservatism, new non-quadratic stabilization conditions are also proposed by applying a new parameter-dependent Lyapunov function, matrix transformation technique, and relaxed technique for the underlying discrete-time 2-D T-S fuzzy system. Finally, a numerical example is provided to illustrate the effectiveness of the proposed results.

Mixed Gl2／GH2 multi-channel multi-objective control synthesis for discrete time systems

This paper proposes a new approach for multi-objective robust control. The approach extends the standard generalized l2 (Gl2) and generalized H2 (GH2) conditions to a set of new linear matrix inequality (LMI) constraints based on a new stability condition. A technique for variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis variables. Consequently, the multi-channel multi-objective mixed Gl2/GH2 control problem can be solved less conservatively using computationally tractable algorithms developed in the paper.

Development of Preparation Systems with K_2CsSb Photocathodes and Study on the Preparation Process

The next generation of advanced light sources requires photons with large average flux and high brightness,which needs advanced electron gun matched with excellent photocathode materials. K_2CsSb photocathode has the advantages of high quantum efficiency, long lifetime and instantaneous response. This study introduces the design of a set of K_2CsSb photocathode preparation systems and detailed preparation process of K_2CsSb photocathodes, including sequential deposition process and co-deposition process, and finally develops a K_2CsSb photocathode. The influence of laser power on the quantum efficiency is also investigated.

Distributed H2/H∞ Filter Design for Discrete-Time Switched Systems

This paper addresses an infinite horizon distributed H2/H∞ filtering for discrete-time systems under conditions of bounded power and white stochastic signals. The filter algorithm is designed by computing a pair of gains namely the estimator and the coupling. Herein, we implement a filter to estimate unknown parameters such that the closed-loop multi-sensor accomplishes the desired performances of the proposed H2 and H∞ schemes over a finite horizon. A switched strategy is implemented to switch between the states once the operation conditions have changed due to disturbances. It is shown that the stability of the overall filtering-error system with H2/H∞ performance can be established if a piecewise-quadratic Lyapunov function is properly constructed. A simulation example is given to show the effectiveness of the proposed approach.

系统性红斑狼疮患者血清miR-125b-5p水平与Th1/Th2细胞、Th17/Treg细胞失衡的相关性

目的探讨系统性红斑狼疮(SLE)患者血清微小核糖核酸-125b-5p(miR-125b-5p)水平与辅助性T细胞(Th)1/Th2、Th17/调节性T细胞(Treg)失衡的相关性。方法选取2021年1月至2023年1月该院收治的88例SLE患者作为SLE组,另选取同期在该院体检的29例体检健康者作为对照组。SLE组根据疾病活动程度分为轻度组、中度组和重度组。检测所有研究对象血清miR-125b-5p水平和外周血Th1、Th2、Th17、Treg细胞比例。采用Spearman相关分析SLE患者血清miR-125b-5p水平与SLE疾病活动程度之间的相关性,外周血Th1、Th2、Th17、Treg细胞比例及Th1/Th2细胞、Th17/Treg细胞比值与SLE疾病活动程度之间的相关性。采用Pearson相关分析SLE患者血清miR-125b-5p水平与外周血Th1、Th2、Th17、Treg细胞比例及Th1/Th2细胞比值、Th17/Treg细胞比值之间的相关性。结果SLE组血清miR-125b-5p水平及外周血Th2、Treg细胞比例均低于对照组(P<0.05),外周血Th1、Th17细胞比例和Th1/Th2细胞、Th17/Treg细胞比值均高于对照组(P<0.05)。SLE患者轻度组35例、中度组30例、重度组23例。血清miR-125b-5p和外周血Th2、Treg细胞比例表现为轻度组>中度组>重度组,外周血Th1、Th17细胞比例和Th1/Th2细胞、Th17/Tre细胞比值表现为轻度组<中度组<重度组,且任意两组间比较,差异均有统计学意义(P<0.05)。Spearman相关分析结果显示,SLE患者血清miR-125b-5p水平与SLE疾病活动程度呈负相关(r=-0.811,P<0.001),外周血Th1、Th17细胞比例及Th1/Th2细胞、Th17/Treg细胞比值与SLE疾病活动程度呈正相关(r=0.728、0.786、0.812、0.808,P<0.001),外周血Th2、Treg细胞比例与SLE疾病活动程度呈负相关(r=-0.811、-0.723,P<0.001)。Pearson相关分析结果显示,SLE患者血清miR-125b-5p水平与外周血Th1、Th17细胞比例及Th1/Th2细胞、Th17/Treg细胞比值呈负相关(r=-0.801、-0.781、-0.816、-0.819,P<0.001),与外周血Th2、Treg细胞比例呈正相关(r=0.845、0.812,P<0.001)。结论SLE患者血清miR-125b-5p水平降低,能通过调节Th1/Th2细胞、Th17/Treg细胞平衡参与SLE的发生、发展。

Feedback iterative learning control for time-delay systems based on 2D analysis approach

This paper deals with the iterative learning control （ILC） design for multiple-input multiple-output （MIMO）,time-delay systems （TDS）.Two feedback ILC schemes are considered using the so-called two-dimensional （2D） analysis approach.It shows that continuous-discrete 2D Roesser systems can be developed to describe the entire learning dynamics of both ILC schemes,based on which necessary and sufficient conditions for their stability can be provided.A numerical example is included to validate the theoretical analysis.

Existence of Al2F-7^- in molten MF–AlF3(M = K, Cs) systems as determined by Raman spectroscopy and structural simulation

The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F-7^-in such molten systems is disputed.In the present study,MF-AlF3(M=K,Cs)systems with molar ratios<1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF6^(3-),AlF5^(2-),and AlF4^-,the systems also contained Al2F-7^-.The characteristic bands in the Raman spectra belonging to Al2F-7^-were located at about 225 cm^-1,315 cm^-1,479 cm^-1,and 720 cm^-1.There are two possible structures of Al2F-7^-,which belong to the D3d and D3hpoint groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.

Entanglement in Spin-1／2 Dimerized Heisenberg Systems

We study entanglement in dimerized Heisenberg systems. In particular, we give exact results of groundstate pairwise entanglement for the four-qubit model by identifying a Z2 symmetry. Although the entanglements cannot identify the critical point of the system, the mean entanglement of the nearest-neighbor qubits really does, namely, it reaches a maximum at the critical point.

Geothermo-mechanical alterations due to heat energy extraction in enhanced geothermal systems: Overview and prospective directions

Geothermal energy from deep underground (or geological) formations,with or without its combination with carbon capture and storage (CCS),can be a key technology to mitigate anthropogenic greenhouse gas emissions and meet the 2050 net‐zero carbon emission target.Geothermal resources in low‐permeability and medium‐and high‐temperature reservoirs in sedimentary sequence require hydraulic stimulation for enhanced geothermal systems (EGS).However,fluid migration for geothermal energy in EGS or with potential CO_(2) storage in a CO_(2)‐EGS are both dependent on the in situ flow pathway network created by induced fluid injection.These thermo‐mechanical interactions can be complex and induce varying alterations in the mechanical response when the working fluid is water (in EGS) or supercritical CO_(2)(in CO_(2)‐EGS),which could impact the geothermal energy recovery from geological formations.Therefore,there is a need for a deeper understanding of the heat extraction process in EGS and CO_(2)‐EGS.This study presents a systematic review of the effects of changes in mechanical properties and behavior of deep underground rocks on the induced flow pathway and heat recovery in EGS reservoirs with or without CO_(2) storage in CO_(2) ‐EGS.Further,we proposed waterless‐stimulated EGS as an alternative approach to improve heat energy extraction in EGS.Lastly,based on the results of our literature review and proposed ideas,we recommend promising areas of investigation that may provide more insights into understanding geothermo‐mechanics to further stimulate new research studies and accelerate the development of geothermal energy as a viable clean energy technology.

Enhanced LMI Representations for H2 Performance of Polytopic Uncertain Systems: Continuous-time Case

Based on two recent results, several new criteria of H2 performance for continuous-time linear systems are established by introducing two slack matrices. When used in robust analysis of systems with polytopic uncertainties, they can reduce conservatism inherent in the earlier quadratic method and the established parameter-dependent Lyapunov function approach. Two numerical examples are included to illustrate the feasibility and advantage of the proposed representations.

Paleo-Fluvial Systems during Marine Isotope Stages 6, 4 and 2 in the North Yellow Sea

Objective During the sea-level lowstands of the Late Quatemary, paleo-channels resulting from large-scale glacial regressions were extensively developed on continental shelves worldwide. Great attention has been paid to the mechanisms and ages of these successions of fluvial incisions, which provide insight into the sedimentary evolution and processes of shelves.

A Prediction of the Excess Partial Molar Free Energies of MgCl_2 in the KCI-MgCl_2-LiCl Molten Salt System Containing MgCl_2 below 0.5 from Thermodynamic Properties of Binary Systems

The thermodynamical properties of MgCl_2 in KCI-MgCl_2-LiCl molten electrolytes containing MgCl_2 below 0.5 (mole fraction, the same below) have been determined from the interchange energies of two binary systems KCI-MgCl_2 and LiCI-MgCl_2, by means of a model on the assumptions that the electrolytes in the solution are treated as independent particles instead of their ion forms and the interchange energy between the component pair KCI-LiCl is ignored when compared with those of component pairs KCl-MgCl_2 and MgCl_2-LiCl. The interchange energies, wKCl-MgCl_2 and wMgcCl_2-Licl, are obtained as-70000 and -13800 J.mol-1, from the corresponding binary solutions, respectively.

Duality of 2-D singular systems of Roesser models

In this paper, the properties and concepts of dual systems of the two-dimensional singular Roesser models （2-D SRM） are studied. Two different concepts of the dual systems are proposed for the 2-D SRM. One is derived from the duality defined for two-dimensional singular general models （2-D SGM）-called the S-dual systems; the other one is defined based on 2-D SRM in a traditional sense-called the T-dual systems. It is shown that if a 2-D SRM is jump-mode free or jump-mode reachable, then it can be equivalently transformed into a canonical form of a 2-D SRM, for which the T-duality and the S-duality are equivalent. This will be of some perspective applications in the robust control of 2-D SRM.

H_∞ Control for 2-D Discrete State Delayed Systems in the Second FM Model

这份报纸涉及 H 控制的问题为二维(2-D ) 分离州的延期系统由第二 Fornasini 和 Marchesini (FM ) 描述了州空间当模特儿。为这个 2-D 系统有 H 噪音变细的一个足够的条件以某个线性矩阵不平等(LMI ) 被给。最佳的 H 控制器被解决一个凸的优化问题获得。最后，一个模拟例子被给说明建议结果的有效性。